The present invention relates to an ink supply device for use in a recording apparatus utilizing liquid ink such as an ink-jet recording apparatus, for example, and more particularly to a recording apparatus using such an ink supply device.
A known ink supply device of the sort described in U.S. Pat. No. 5,158,377 for a recording apparatus using liquid ink, for example, is adapted so that ink is supplied to a print head by directly pressing a porous member for holding ink against a capillary member which is provided for the print head.
In the recording apparatus like this, it has been so arranged that a suitable negative pressure is maintained in a print head. In the case of an ink-jet pen as described in the Unexamined Japanese Patent Application Publication No. Hei 3-180357, bubbles corresponding the volume of ink to be consumed is introduced from a bubble generator in a hermetically-sealed housing so as to store the ink with the negative pressure maintained therein. Notwithstanding, no consideration has been given to the problem of an outflow of ink, depending on the position of the housing.
Each of the ink supply devices of FIGS. 7 to 11 has, as described in the Unexamined Japanese Patent Application Publications No. Hei 7-52405 and No. Hei 7-81084, a main ink chamber communicating with a print head, a sub ink chamber with a capillary member disposed therein, a meniscus forming member having a number of pores provided in part of the wall of the main ink chamber, and an ink supply member for supplying a liquid to the meniscus forming member, wherein the bubble point differential pressure formed in the pores of the meniscus forming member by the ink supplied via the ink supply member keeps the pressure inside the ink chamber negative.
In such an ink supply device as mentioned above, the bubble point pressure in the meniscus forming member causes air to be introduced into the intermediate ink chamber as ink is consumed when the printing operation is performed by the print head. When the position of the print head varies in the state above due to the variation of the installation position of an printer body, the replacement of the print head or the ink supply device left alone after being separated from the recording apparatus, the ink in the main ink chamber is moved while being attracted by the capillary member in the sub ink chamber and the atmospheric air kept in contact with the meniscus forming member of the sub ink chamber is allowed to penetrate into the main ink chamber in the form of bubbles instead; the problem is that because the ink is replaced with the air, the residual ink may become unusable at the time the remaining printing condition is restored.
Even in the ink supply device of FIGS. 4 to 6 with the ink chamber and the ink chamber equipped with the capillary member being vertically arranged according to the Unexamined Japanese Patent Application Publication No. 7-81084, there is raised the same problem, depending on the position of the ink supply device.
Particularly when the position of the ink supply device varies often, it also poses a serious problem that ink is replaced with the air in the ink chamber.